This invention relates to certain insecticidal or antiviral compounds classified as justicidins, to insecticidal and antiviral compositions containing these compounds, and to methods of using the compositions to kill insects or to treat viral infection in mammals.
Natural 1-aryl-2- or -3-napthoic acid lignan compounds have previously been isolated from various sources. Some of these compounds have been associated with bioactive properties.
Ohta, et al., Agr. Biol. Chem. 33:610-614 (1969), describe the isolation of justicidins A and B, and report that these compounds are active piscicidal components of Justicia Hayatai var. decumbens, a herbaceous annular historically employed by Taiwanese natives to harvest fish. In later publications, e.g., Ohta, et al., Tetrahedron Letters, No. 43, pp. 923-925 (1970); Chen, Proc. 5th Asian Congress Pharm. Sci. Fed., 1-7 Dec. 1974, pp. 79-86; the structure of justicidin A was assigned as set forth below: ##STR2##
Justicidin B, which lacks the B-ring methoxy substituent of justicidin A, and a related compound are disclosed in Munakata, U.S. Pat. No. 3,704,247. This patent discloses that justicidin A and B exhibit extraordinary piscicidal activity, but does not disclose insecticidal activity, although synergistic behavior was observed when mixtures of justicidin A and B and pyrethrin or allethrin were tested against mosquito larvae of the species Culex pipiens pallens.
Ghosal, et al., Chem. and Ind., 854-855 (1979), described isolation and purification of prostalidins A, B and C from Justicia prostata C. B. Cl. Gamble, an antidepressant folk medicine. The structure of the prostalidins is set forth below:
______________________________________ ##STR3## R.sup.1 R.sup.2 ______________________________________ Prostalidin A H OMe Prostalidin B Me OMe Prostalidin C H H ______________________________________
Markannen, et al., Drugs Exptl. Clin. Res. VII(6): 711-718 (1981), disclose antiviral activity of certain podophyllotoxin lignans when tested against Herpes simplex Type-1 virus in mammalian cell cultures. However, none of the compounds tested by Markannen contain either an aromatic B-ring or a methoxylated lactone ring.